1. Technical Field
The present invention relates to a method of half-cut cutout processing of label paper, which allows laser beam to cut only a label sheet of the label paper into a given cutout shape.
2. Background Art
A variety of label paper has hitherto been proposed, the label paper comprising a label sheet and a supporting sheet stuck together with a pressure-sensitive adhesive wherein only the label sheet of the label paper is cut into given cutout shapes, each of which may individually be peeled off from the supporting sheet for use as a label or the like.
And, a variety of ways of half-cut cutout processing of label paper have also be proposed that allows laser beam to cut only a label sheet of the label paper.
For example, as disclosed in JP 2000-231335 A, a method of half-cut cutout processing of label paper has been proposed in which the label paper has a label sheet (main film) and a supporting sheet (base film) stuck together with a pressure-sensitive adhesive and surface of the label sheet is irradiated with laser beam (laser light ray) and thereby only the label sheet of the label paper is cut into given cutout shapes.
A depth of cut into a surface of a label sheet irradiated with laser beam as mentioned above is determined by a processing energy of the laser beam and a color of the surface of the label sheet.
To wit, the larger and smaller the processing energy of the laser beam becomes, the greater and smaller the depth of cut becomes, respectively. And, the darker and brighter the color of the label sheet surface becomes, the higher and lower the absorption efficiency of the laser beam becomes, hence the greater and smaller the depth of cut becomes, respectively.
A processing energy of laser beam is determined by an output, an irradiation time and an irradiation density of the laser beam.
On the other hand, on a surface of the label sheet there is printed a print image such as of a character and a figure, which has been printed before cutting of the label sheet.
And, there are both the case where cutting is effected over a region not of the printed image (e.g., a blank portion outside of the periphery of the printed image) and the case where cutting is effected over a region of the printed image (e. g. a portion in the printed image which is closer to its periphery when it is printed all over the surface) and also the case where cutting is effected over both a region not of the printed image and a region of the printed image. In any of the cases, it is required that a depth of cut correspond to a thickness of the label sheet so as not to cause the supporting sheet to be damaged by the laser beam.
Thus, in the case where cutting is effected in a region not of a printed image on the label sheet, the requirement for a processing energy of the laser beam corresponding to a color in a surface of the label sheet will, when label sheets of different surface colors are to be cut, require that the processing energy of laser beam be adjusted and controlled for each of the label sheets of different surface colors, making the cutting operations complicated and burdensome.
Also, in the case where cutting is effected in a region of a printed image on the label sheet, a requirement for the printed image having a plurality of portions of different colors will require that the processing energy of laser beam be frequently adjusted and controlled in cutting each of different printed color portions, namely during each cutting operation, rendering the operation highly complicated and burdensome.
Also in the case where cutting is effected over both a region of and a region not of a printed image, it is required that the processing energy be adjusted and controlled as in both the cases mentioned above, making the cutting operations very complicated and burdensome.
Made in view of the aforementioned problems, the present invention has for its object to provide an improved method of half-cut cutout processing of label paper which allows a label sheet to be cut by laser beam without damaging a supporting sheet and which is simple in adjustment and control of a processing energy of the laser beam, reducing the burdensomeness of the cutting operation and operations.